Primary defences Flashcards
What does non-specific mean?
Works against a range of pathogens, not dependant on specific antigens being present
How is the skin a defence mechanism
There a keratinised cells on the outer layer that stop pathogens from entering
What happens in on the skin to the cells
The cells cytoplasm is replaced by keratin so the cells die
What oil is produced on the skin?
Sebum is produced which has anti-bacterial properties
What does blood clotting do?
Blocks open wounds quickly as prevents pathogens from entering the blood stream
What does wound repair do?
Re-form the protective barrier of the skin
What do explosive reflexes do?
Removes pathogens from nose, lungs and stomach by vomiting or sneezing
What does mucus do?
Goblet cells
What does mucus do?
Mucus traps pathogens
How does mucus work with ciliates epithelium?
They waft the mucus with the pathogen away
What do cells release when they are damaged?
Histamines
What do histamines cause?
Inflation
What do histamines do?
They vasodilate so there is an increased blood flow as well as red and swelling making capillaries more permeable/ leaky so more red blood cells arrive
Why do plants release chemicals as a defence?
They provide anti microbial chemicals to defend themselves from pathogens
What are the plant chemicals targets?
They want to stop the pathogen from developing a cell wall so they have no structure
What happens when a pathogen has no cell wall?
It will burst as soon as it goes into water and kill the pathogen and inhibit or stop growth
What does the plants waxy cuticle and bark do?
It acts as a barrier to stop the pathogen from entering and stops water from collecting on leaves so pathogens can’t grow
How do pathogens spread in plants?
In the plasmodesmata which are the connections between neighbouring cells
What happens to the plasmodesmata when a plant is infected?
It is blocked by deuce plates called callose at the end of growth season
What does lignin do?
It thickens the cell wall of xylem vessels so is more waterproof and less indigestible so it is less likely to allow a pathogen to enter or leave the cell
What happens to stomatas
Pathogens can go through them so they are closed when unused to limit pathogen entry
What is tylose formation
A balloon like swelling that block xylem vessels so a pathogen can’t go around the plant
What do oxidative bursts do?
Produce highly reactive oxygen molecules that can damage invading pathogens
What are terpenoids used for?
A range of essential oils that have many antibacterial and antifungal properties and can also make a scent like mint and menthons/ menthols
What are phenols used for?
These have antibacterial and antifungal properties
What are tannins used for?
It is a phenol in bark that inhibit attack by insects. They ban to salivary proteins and digestive enzymes such as trypsin and chymotrysin, deactivating the enzymes that can kill insects of eating in large doses
What are alkaloids used for with taste?
Nitrogen - containing compounds, such as nicotine, caffeine, cocaine, morphine and solanine to give it a bitter taste to herbivores.
What are alkaloids used for with metabolic reactions?
They can inhibit or activate enzymes actions such as inhibiting protein synthesis
What are defensive proteins?
These are small cysteine-rich proteins that happens have a broad anti-mixrobtial activity. They attack plasma membranes of pathogens to inhibit the ion transport channels
What do hydrolytic enzymes?
These are found between the cells to kill pathogens
What does chitinase do?
Break down the chitin found in fungal cells?
What does glucanase do?
Hydrolyse the glycosidic bonds in glucans
What do lysosomes do?
They can degrade bacterial cell walls
What is necrosis?
Deliberate cell suicide by a small part of a plant to protect the rest of the plant and to stop the infected part from receiving any nutrients
What is a cranker?
A sunken necrotic lesion in the woody tissue such as the main stem or Branch that caused the death of the cambium tissue in the bark
How does the digestive system protect against pathogens?
Acid in the stomach kills them
The lower pH kills them and disrupts their enzymes
